Pope Gregory IX

Pope Gregory IX (1145-22 August 1241), born Ugolino di Conti, was Pope from  1227 to 1241, succeeding Pope Honorius III and preceding Pope Celestine IV.

Biography
Ugolino was made a cardinal in December 1198 by Pope Innocent III, and he was elected as pope in 1227. Gregory had a rivalry with Frederick II of Germany, starting when Frederick did not invade the Holy Land as promised. He eventually invaded the Holy Land, but while he was gone, the Governor of Spoleto Rainald invaded the Papal States, causing Gregory not to trust Frederick. He invaded Sicily, but Frederick returned in time to force Gregory to make peace with him after defeating his army. Gregory also demonized black cats, saying that they were the Devil, and he also persecuted perceived heretics in the Papal Inquisition.